Abstract Type 2 Diabetes Mellitus (DM) is a preventable chronic disease that affects 9.3% of US adults and children. It is estimated that 86 million American adults are prediabetic (37%), and thus at risk of DM and cardiovascular disease. DM is a leading cause of death, one of the major causes of heart disease and stroke, and severely threatens quality of life. DM more than doubles the health care costs compared to the general population. Safety-net institutions like Bellevue Hospital Center (BH) and the VA NY Harbor Healthcare System (VA) care for populations with a disproportionate burden of DM and DM risk. Nearly 25% of the 8.7 million US veterans have DM and the rate among Bellevue?s 30,000 primary care adult patients is more than 15%. Despite the potential for reduced morbidity and cost-savings, primary care systems must overcome several barriers to systematically deliver these proven, preventive strategies to patients at highest risk of DM. Employing community health worker (CHW) coaches to conduct behavioral counseling, follow-up referral to programs, and education is a promising approach that could extend the capacity of health systems to better prevent and manage chronic conditions. Despite the potential for peer-led intervention to enhance DM prevention efforts within the patient-centered medical home (PCMH) model, there is need for high quality, randomized trials to asses specific models for CHW support; to aid with implementation of such model, including identification of effective strategies for recruitment, training, monitoring and retention of lay personnel; and to successfully integrate these personnel within the PCMH. The goal of this proposal study is to develop and test a model of CHW health coaching, designed to prevent the onset of Type 2 DM in a large population of underserved patients at risk. CHWs will be recruited from the target populations and trained in core competencies to serve as peer health coaches. Our central premise is that CHWs are uniquely suited to engage fellow patients by encouraging lifestyle change through shared experiences and social support to extend the reach of primary care (PC) beyond the clinic visit. This study will test a scalable model of peer health coaching to address the millions of patients at risk for DM, using low cost, culturally congruent personnel to promote prevention of DM in PCMH practice.